Machine tool and hydraulic operating mechanism therefor



May 16, 1939 Q R ALDEN 2,158,060

MACHINE TOOL AND HYDRAULIC OPERATING MECHANISM THEREFOR Filed Ap ril :50, 1934 e Sheets-Sheet 1 if a J58 YTWENTO y 1939. c. R. ALDEN 2,158,060

MACHINE TOOL AND HYDRAULIC OPERATING MECHANISM THEREFOR Filed April 50, 1934 9 Sheets-Sheet 2 TFNLNTOQ Car/0)) Rcfl/den q-r-Tor NE s C. R. ALDEN May 16, 1939.

MACHINE TOOL AND HYDRAULIC OPERATING MECHANISM THEREFOR 9 Sheets-Shet 3 Filed April 30, 1934 TNVE NTo 00270)) /P. when W I M ATTOIQNE S y 1939. c R. ALDEN 2,158,060

MACHINE TOOL AND HYDRAULIC OPERATING MECHANISM THEREFOR Filed April 30. 1954 9 Sheets-Sheet 4 IrvvEN-m Carroll J7 JTTTORNEYS.

May 16, 1939. c R, ALDEN 2,158,060

MACHINE TOOL AND HYDRAULIC OPERATING MECHANISM THEREFOR Filed April 30, 1934 9 Sheets-Sheet 5 was C. R. ALDEN May 16, 1939.

MACHINE TOOL AND HYDRAULIC OPERATING MECHANISM THEREFOR Filed April 30, 1934 9 Sheets-Sheet 6 s Q N O Q N T d P\ L m DION mg W M T dwm T p w om an an M mo. M .-W wm m m a mm mm 1 8 on w Q 8 L AR mm. mm .3x ww awd m r P, R m wmx \.\\W a Jig r 7%/ u QM 9 Sheets-Sheet 7 TNENTQ w n W T 5W M r w C, R. ALDEN Filed April 30, 1934 May 16, 1939.

MACHINE TOOL AND HYDRAULIC OPERATING MECHANISM THEREFOR y 6, 1939. c. R. ALDEN 2,158,060

led April 30, 1934 9 Sheets-Sheet 8 mvsm-rolg y 1939- c, R. ALDEN 2,158,060

MACHINE TOOL AND HYDRAULIC OPERATING MECHANISM THEREFOR Filed April 30. 193 9 Sheets-Sheet 9 l E JG. 1/ Ti 90 I 92 I g l =5 V \jf v80 J69 J68 fivENTor Patented May 16, 1939 UNITED STATES MACHINE TOOL AND HYDRAULIC OPERAT- ING MECHANISM THEREFOR Carroll It. Alden, Detroit, Mlcln, assignor to Ex- Cell-O Corporation, a corporation of Michi- Application April :0, i034, Serial No. 123.135

, 26, Claims. The present invention relates to improvements in machine-tools, and has particular reference to relatively slow feed movement in either direc-,

tion, of means selectively adjustable to obtain a slower rate of feed in either direction than in the 16 opposite direction.

A more detailed object is to provide an hydrauiic operating mechanism' of the foregoing character comprising a reversible hydraulic motor. two fluid supply and discharge conduits con-- nected respectively to the opposite ends of the motor, a pressure conduit and an unrestricted exhaust conduit, direction valve means for respectively connecting the first mentioned conduits reversibly to-the pressure and supply conduits, two restricted exhaust conduits branching re-' 'spectively from the first mentioned conduits in parallel with the unrestricted exhaust conduit and each including an independently adjustable ieed control orifice, and valve means for opening and closing the unrestricted exhaust conduit to eil'ect respectively a rapid traverse or the discharge of fluid from the motor through one or the other of the restricted exhaust conduits to obtain a slow teed.

Another object resides in the provision oi novel means for automatically adjusting one of the feed control orifices to ehange the rate of feed during movement of the carriage in one direction through a predetermined range.

A further object resides in the provision, in a new and improved hydraulic operating mechanism comprising an hydraulic motor for reciprocating the carriage, a direction valve for controlling the operation of the motor, and two pilot reset 5 valves responsive to the movement of the carriage respectively into opposite end positions for reverging the direction valve, of spindle brake and switch hydraulic actuators in parallel with -the direction valve and controlled directly by the sui pilot reset valves.

, A iurtherf-object resides in the provision, in an hydraulic operating mechanism reversible under ".control of dogs on the carriage, of a novel niech'anism operable upon rendering one 55 of the doe's ective to provide a dwell at one end of the carriage movement, and then to automatically adjust the operating mechanism to reverse the movement of the carriage.

Still another object is to provide a new and improved hydraulic operating mechanism, comprising an automatic stop valve operable by the carriage, which is pressure relieved upon actuation of the stop valve.

A further object resides in the provision of a novel hydraulic operating mechanism having two pilot reset reversing valves and two pilot reset rapid traverse and feed control valves, operable selectively by the carriage, in which a reversal of the carriage in one direction may be obtained either by actuating one of the reversing valves in one direction or the other reversing valve in the opposite direction, and in which a change from rapid traverse to feed or vice versa may be obtained by actuating one of the controivalves in one direction or the other control valve in the opposite direction.

Further objects and advantages will become apparent as the description proceeds.

In the accompanying drawings, Figure 1 is a front elevational view 01' a machine embodying the features of my invention.

Fig. 2 is a rear elevational view 0! the machine.

Fig. 3 is a diagrammatic representation of one form of the hydraulic operating mechanism with the parts adjusted for a slow feed traverse of the carriage to the right.

Fig. 8 is a fragmentary view of one of the valves illustrated in Fig. 3 but showing same in its other position of adjustment.

Fig. 4 is a diagrammatic representation of another form of the hydraulic operating mechanism with the parts adjusted for a rapid traverse of the carriage to the left.

Fig. 4' is a iragmentaryview oi one of the valves illustrated in Fig.4 but showing same in its other position of adjustment.

Fig. 5 is a side elevational view oi a unitary control structure mounted in the front of the machine, and enclosing the various direction and speed valves embodied in the system of Fig. 3;

Fig. 6 is a fragmentary plan view of the control structure, partially in composite section along-lines 66, G' -8', and i -6 of Fig. 5.

Fig. 'l is a vertical sectional view taken substantially along broken line 1-1 of Fig. 6. i

Fig. 8 is a fragmentary sectional view taken along line 0-8 of Fig.5. Fig. 9 is a fragmentary sectional view taken along line 8-9 of Fig. 2, and showing a feed control valve in side elevation.

Fig. 10 is a trontelevational view of a feed adlusting unit controlled by the feed valve.

Fig. 11 is a transverse sectional view, taken along line il--ll of Fig. 10, of the control structure shown in Fig. 5 with the feed adjusting unit attached.

Referring more particularly to the drawings, the invention, for purposes of illustration, is disclosed as embodied in a machine tool (see Figs. 1 and 2) comprising an elongated hollow base i on the top of which a carriage l is mounted for longitudinal reciprocation, and which is formed on the opposite sides of one end with auxiliary guideways 9 parallel to the direction of movement of the carriage. An inverted U-shaped bridge member 4 is rigidly mounted on the guideways I for adjustment longitudinally of the base I, and

serves as a support for one or more, for example two, parallel brackets I. Rotary spindles ii are Journaled respectively in the brackets i, and are adapted to be driven i m a suitable source of power, such as an electri motor I.

The motor 'i is provided with a suitable braking mechanism for stopping the rotation of the spindles 9. In the present instance. the braking,

A pressure fluid responsive piston II slidable in a cylinder I4 is directly attached to the rod i2, and upon reciprocation in oppositedirection acts to apply and release the band ll.

Any suitable circuits maybe provided for energizing the motor I. In the present instance, the motor I is of the alternating current type, and is adapted to be connected to electric supply lines L1. La and Lo by a magnetic switch I! havin an actuating coil ii. A control switch I! is adapted to close a circuit'through the coil iii as follows: from the main line L1, through a line II, a fixed contact ll, a movable contact 29, a fixed contact ii, a line 22, the coil i6, and a line 23 to the main line In. The movable contact is operable through a reciprocatory rod-I4 connected to a pressure fluid responsive piston 25 slidable in a cylinder 2!.

It will be understood that a similar spindle head structure may be provided at the other end of the base i to constitute the machine tool one of the double end type similar to that disclosed inmy said copending application. Figs. 3 and 4 illustrate a motor control circuit and abraklng mechanism for such duplicate structure, and the corresponding parts thereof are identified by the same reference numerals distinguished by the exponent "a". Preferably, the movable contacts III and 20} are connected for joint actuation so that upon movement of the piston 28 in one direction, the contact III will bridge the contacts I9 and Il to institute the operation of the n'iotor I, and upon movement of the piston in the reverse direction, the contact 29 will bridge the contacts I! and II to instituteoperatlon of the motor I The present invention relates primarily to an hydraulic operating mechanism fol-moving the. carriage 2 and actuating the brake pistons I3 and II and the switch piston 25. In its ferred form. the operating mechanism com I an hydraulic motor (see Figs. 3 and 4) ngsg;

cylinder 21 mounted in fixed position within the base i, and a piston 21 reciprocable in the cylin- .der and connected through a piston rod 28 to the carriage 2. Opening from the cylinder 21 respectively at opposite sides of the piston 21' are The direction valve ll (see Figs. 3 and 6) may be of any desired construction, and preferably comprises an elongated cylinder bore 32 closed at opposite ends and formed in a valve casing 33. A valve piston 84 of the spool type, comprising axially spaced heads and 36 separated by an annular space 31, is mounted for reciprocation in the bore 32. Opening through the casing 33 to the bore 32 intermediate its ends are two longitudinally spaced pressure ports 88 and 39, and, between-the latter, two longitudinally spaced exhaust ports and 4|. These ports are so, arranged that when the piston 34 is in one end position, the ports 38 and 4i will be closed by the heads 35 and 39, and the ports 40 and 39 will be open-respectively to the space 91 and one end of the bore 42, and when the piston occupies the opposite end position, the ports 38 and 4| will be open respectively to the other end of the bore 82 and the space 31, and the ports 39 and 40 will be closed. The ports 38 and 40 are connected in parallel to the conduit 29, and the ports 39' and 4i are similarly connected to the conduit. Fluid supply and discharge ports 42 and 43 open respectively to opposite ends of the bore 32, and are connected to conduits 44 and 45. An exhaust port 46, connected to a conduit 41, opens to the bore 32 between the ports 40 and H, and is always in communication with the space 31.

The conduits 44 and 45 are adapted to be connected respectively and reversibly by an automatic reset pilot direction control to a suitable source of pressure fluid, such as a constant flow pump 40 having a pressure relief overflow 49, and a drain, such as a sump 50, to control the position of the valve piston 34, and thereby the direction of operation oi the motor piston 21'. It will be evident that when the port 43 is connected to the pump 48 and the port 42 is connected to the sump ill, the valve piston 34 will be moved into its left hand position. Thereupon, fluid will be supplied to the conduit 30 and exhausted from the conduit 29 to effect movement of the piston 21- and hence the carriage 2 to the right (see Fig. 3). Upon connecting the port 42 to the pump 48 and the port 43 to the sump ill (see Fig. 4), the movement of the carriage 2 will be reversed. I

The automatic reset pilot direction control (see Figs. 3, 4, 6 and 'l) is responsive to the movement of the carriage 2, and comprises two valves BI and I! for eil'ecting reversal of the carriage respectively to the left and right. These valves respectively comprise chambers or cylinder bores BI and 54 which may be formed in any suitable caslugs, and which in the present instance open vertically through a plate or apron" secured to the front of the base i over an opening 58. Each 01 the cylinder bores 53 and 64 is closed at its lower end .by a screw plug 51' having an upwardly projecting axial stop 58, and has a bushing I9 secured in its upper end. 4

Respectively disposed in the cylinder bores '3 a t a! for reciprocation between the stops I8 ythe bushings 59 are two valve pistons ill and Bi V of the spool type provided respectively with actuating plungers 62 and 88 extending through the bushings for external engagement. The piston Bil is formed in its periphery with longitudinally spaced annular grooves 84 and 88 in communicatlon with an axial passage 88. Similarly,

the piston 8| has two longitudinally spaced peripheral grooves 81 and 88 opening to an axial passage 88,. a

A branch'ed conduit l8 opens constantly to the bores 53 and 84 above the pistons 88 and 8|, and is adapted to supply, subject to control by a stop valve H, motive fluid under full pressure from 18 the pump 48. The conduits 44 and 48 from the direction valve 8| open respectively to the cylinder bores 53 and 54 from selective connection with the pressure conduit 18 when the related pistons 88 and Bi are lowered against the stops 58,

i8 and with the grooves 88 and 88 when the pistons are raised against the bushings 88. Cross conduits 12 and I3 respectively branch from the conduits 44 and 48, and open constantly to the lower ends of the bores 54 and 53. Also opening to- 80 the bores 83 and 54 for communication respectively with the grooves 84 and 81 when the related pistons 88 and 8| are in their uppermost positions is a drain conduit I4 discharging to the sump 88. The upper ends of the plungers 82 and 83 are beveled to constitute reversing abutments adapted for engagement by suitable control dogs 18 and 18 mounted on the front of the carriage 2.

Assuming that fluid under pressure is available in the conduit 18 and that the plunger 83 is depressed (see Fig. 3), pressure fluid will be supplied from the conduit 18, through the cylinder bore 84, and the conduit 45 to the right end of the direction valve bore 32, and from the conduit 45 through the cross conduit 13 to the lower end of the bore 83. Thereupon, the piston 88, by reason of its diflerential areas, will be raised into its uppermost position to connect the left end of the bore 32 and the lower end of the bore84 through the conduits 44 and I2, the groove 85, the passage 68, and the groove 84 to the drain conduit I4. As a result, the plunger 83 will be retained in its lowermost position, and the direction valve piston 34 will be moved to the left to institute movement of the carriage 2 to the right. When the 45 carriage 2 reaches its right limit position, the dog 15 will depress the plunger 82 to lower the valve piston 88, the fluid in the chamber 53 being backed up into the conduit I3 against the pressure in the connection to the source. Thereupon the conduits 4,4 and I2 will be connected to the pressure conduit 18 to elevate the valve piston 8|, and then the conduits. and 12 will be connected to the drain conduit I4. This will reverse the di rection valve 3| to institute movement of the 5 carriage 2 to the left (see Fig. 4). "At .the left limit position, the dog 16 will again depress the plunger 53 to establish the initially described hydraulic circuits. It will be evident that each of the pilot valves iii and 52 upon being actuated by 80 the carriage 2 not only reverses the direction valve 3|, but also resets the other pilot valve in operative position. v

Provision is made for varying the rate of fluid discharge from-the motor cylinder 21 to obtain a rapid traverse or a feed of the carriage 2 in each direction of movement. For rapid traverse, the exhaust fluid is always discharged through the direction valve 8| to the conduit 41 which is unrestricted, and which is adapted to be closed or connected to the drain co ult 14 by a rapid traverse valve ll. For feed, e exhaust fluid is adapted tobe directed through one or the other of two restricted conduits I8 and I8 respectively branching from the conduits 28 and 38, and leading to the valves ii and 82 for connection to the drain conduit 14 when the valve pistons 88 conduit 18 will be closed by the valve 82 to main- 5 tain the pressure in the conduit 38, and fluid will be discharged from the cylinder 21 through the conduit 28, the conduit 18, and the groove 84 to the drain conduit 14, thereby effecting a slow feed. Conversely, under the same conditions but 1 with the carriage 2 moving to the left, the conduit 18 will be closed, and fluid will be discharged from the cylinder 21 through the conduits 38 and i8 and the groove 81 to the drain conduit [4, thereby effecting a slow feed in the opposite di 15 rection. When the conduit 41 is open (see Fig. 4), the discharge of the fluid will be unrestricted to efiect a rapid traverse.

The feed conduits I8 and 18 are restricted respectively by two orifice valves 88 and 8| (see 99 Fig. 6) which are independently adjustable to vary the rate of feed in either direction. Therefore, since one or the,other of the orifice valves 88 and 8|, depending on the direction of carriage movement, is adapted to be in sole control 5 of the rate of feed, the feed in either direction may be made faster or slower than in the other direction.

The'oriflce valves 88 and 8|, in their preferred form respectively comprises two 0 lindrical valve 30 plugs 82 and 83 rotatably adjusta 'le in bushings 84 and 85 seated in parallel bores 88 and 81 in the front of the apron 55. .A clamping plate 88 removably bolted to the apron 55, and extending at opposite ends respectively through slots 35 88 in the bushings 84 and 85 into annular grooves 88 in the outer ends of the plugs 82 and l 83 serves to retain these parts within the bores 88 and 8.1. The plugs 82 and 83 are provided respectively with adjusting heads 88'normally 40 enclosed by a removable cover plate 8| on the front of the apron 55. Suitable springs 82 interposed between the outer ends of, the bushings 84 and 88 and the heads 88 serve to take up any end play in the plugs 82 and 83.,

The inner ends of the bores 86 and 81 are connected respectively to the conduits l8 and I8, and outlet ports 83 and 84 are'respectively formed in the bushings 84 and 88 and connected to the pilot valves ii and 52. The plugs 82 and so 83 are formed respectively with axial passages 85 opening to the inner ends of the bores 88 and 81, and with peripherally tapered V-shaped groove orifices 88 and 81 opening to the closed ends of the passages 85, and rotatably adjustable 83 longitudinally across the ports 83 and 84. It will be evident that the restrictions in the feed conduits 18 and I8 may be adjusted by varying the angular relationship of the orifices 88 and.

81 to the ports 83 and 84. If the effective size of the opening through the orifice 88 is made less than that through the orifice 81, the carriage feed will be slower to the right than to the left. Conversely, if the portion of the orifice 88 across the port 83 is greater in width than the portion of the orifice 81 communicating with the port 84, the feed will be slower to the left than the right. Obviously, the rate of feed "may be made equal in both directions. 3

[The rapid traverse valve 'l'l comprises a cylin- 7o der bore 88 opening vertically through the apron 55, and closed at its lower end by a screw plug 88 with an inwardly projecting stop I88. A bushing i8| is fixed in the upper end of the bore 88. Slidably disposed in the bore 88 is a valve piston I02 having an axial plunger I03 extending upwardly through the bushing IOI for external actuation. The exhaust and drain conduits 41 and II open to the bore 00, and are adapted to be brought into communication through an annular groove I04 in the piston I02 when the latter is positioned against the stop Ill, and to be blanked when the piston is in its outer end position. Hence, a rapid traverse will be obtained when the'plunger I03 is down, and a ieed movement will result when the plunger is up.

The rapid traverse valve I1 is adapted to be actuated through engagement a dog I05 on the carriage 2 with the plunger I02 to institute rapid traverse, and to be elevated under the control oi a pilot teed valve I00 to institute the feed. In the single end machine the dog I05 is pivotal in one direction out or vertical center position to flip over the plunger I02 upon movement of the carriage 2 to the left, and is arranged to depress the plunger immediately after reversal of the carriage to the right. For a double end machine, two dogs I00 may be provided eil'ective at opposite ends of the carriage movement.

The pilot i'eed valve I00 also comprises a cylirider bore' I01 opening vertically through the apron I0, and closed at its lower end with a screw plug I00 having an inner stop I00. A bushing III is fixed in the upper end 01' the bore I01. Slidably disposed in the bore I01 is a valve piston III having an end plunger II2 extending up-.

wardly through the bushing M0 for external actuation. The pressure conduit I0 opens constantly to the upper end of the bore I0'I. An annular groove H2 in the piston III is always In communication with a drain conduit III discharging to the sump 50. A cross conduit "5 opens from the bore I01 intermediate the con- (hits [0 and I to the lower end or the bore.

ll, and is adapted to be connected to the conduit when the piston III is depressed-and to the conduit I when the piston is elevated. Hence, when the reed plunger H2 is depressed, the traverse plunger I02 will be reset and held in its uppermost position.

, The pilot feed valve I06 is adapted to be actudted by engagement oi. a dog H0 on the carriage 2 with the plunger III to institute the feed, and

to be reset into and held in operative position when the rapid traverse is instituted by depressing the plunger I02. In this connection, it is to be noted that when the plunger I03 is depressed as shownin Fig. 4, a connectionwill be established from the pressure line 10 through the valve II. and the line III to the bore I01, thereby resetting the valve I00, and thereupon the lines III and II are connected to retain the valve I06 in position. For a double end machine, two dogs II! respectively adapted todepress the plunger II2 durini the travel of the carriage 2 in opposite direct ons may be provided.

The pressure conduit I0 opens to the upper end 0'! the valve bore 08, and the drain. conduit Ill opens to the same bore at a lower point. A cross conduit III opens from the lower end of the valve bore in to the bore as intermediate the r conduits l0 and I. adapted to be connected with the pressure condnit II when the piston I02 is down to reset the The cross conduit in is ve m. and with the drain conduit m through anpnnular groove. I II in the piston I02 when the ,Ihus, thetwo valves 11 and I00 act as pilot 75 valves for alternately resetting each other.

the pressure relieved system, the stop valve Ii when actuated to stop the carriage 2 is operative to connect the pressure conduit 10 to the drain conduit I4. This has the advantage that when the machine is idle, the pump is not obliged to deliver fluid against the working pressure normally present in the system. Hence, less power is required, and the dissipation of energy in the form of heat within the machine is substantially avoided. In the second system, designated as the pressure maintained system, the stop valve II is operative to disconnect the pressure conduit 10 from the pump 00, and thereby to trap the motive fluid within the system. This has the advantage that sufllcient pressure is available when desired for operating various hydraulic fixtures that may be used on the machine, for example work fixtures and clamps. In each instance, the stop valve II comprises a chamber or bore H0 opening vertically through the apron 55, with a screw plug I20 closing the lower end and a bushing I2I seated in the upper end, and a valve piston I22 reciprocable in the-bore and having a plunger I22 extending upwardly through the bushing for external actuation.

The plunger I2; is adapted for engagement by a dog I22 pivotal in one direction, for example to the right, out of vertical position on the front of the carriage 2. In the single end machine, the dog I22 is positioned to depress the plunger I23 upon movement of the carriage 2 away from the spindle head structure I, 5, 0 into a remote inoperative position. For the double end machine, the dog I22 may be positioned midway of the dogs and I0, and may be inoperative to depress the plunger I22 in one direction or carrlage movement, for example to the left, so that the carriage cycle may comprise movement from an inoperative intermediate position into one end position, then a reverse movement past the intermediate position into the other end position, and then a return movement tothe intermediate position. It will be understood that if the dog I28- is removed or rendered inoperative, the carriage 2 will reciprocate continuously.

A specific selection and arrangement of reversing, traverse control and stop dogs, for single and double end machines has been disclosed. The invention however is not limited to any particular carriage program. the latter being adapted for variation by the selection and arrangement of carriage dogs to suit theworking requirements or the machine. It a substantial number 01' dogs are required, and these are closely spaced, some of the dogs may be mounted on an auxiliary support (not shown) adapted to be attached to the carriage 2.

Referring first to the valve II illustrated in Fig. 3, the pressure conduit 10 is connected directly to the discharge of the pump 08, andghas three parallel branches I24, I25 and I opening respectively to the valve bore 0 at the upper end, an intermediate point, and the lower end. The exhaust conduit I4 opens to the valve bore I I0 in-the same transverse plane as thebranch conduit I25. The piston I22 when in its uppermostpositi'on blanks the conduits I4 and I25, and is held imposition by the diflerential' pressure acting on its opposite'ends. In this position of the piston I22, the system is at full pressure, and hence; operative. T'he'piston I22 is formed with an annular groove I21 adapted to connect the conduits I4 and I2! to.relieve the pressure when the piston is in its lowermost position.

' The auxiliary drain conduit II4 also opens to the bore H9 at a point between the'branch condults l25 and I26 and is adapted to be connected to the lower end of the bore through an annular groove I28 and a bleed passage I29 formed in the piston I22 when the latter is depressed. The purpose of the bleed connection is to permit the piston I22 to move way down into its lowermost position. When the plunger I23 is depressed to connect the conduits I4 and I25, the piston I22 'will close the conduit I,28 so that the pressure in the lower end of the bore H9 will be completely Hence, the piston I22 will remain in its inoperative position as illustrated in Fig. 3'.

In the pressure relieved system, when the plunger I23 is depressed to stop the carriage 2, one or the other of the valve pistons III2-and III will occupy its uppermost position. To prevent this piston from dropping under its own weight after pressure relief. one of these pistons, for ex'ample the feed valve piston III, is adapted to be held yieldable in either endposition by a spring pressed ball detent I30 (see Figs. 6 and 7) engaging selectively in two longitudinally spaced recesses I3I in the body of the piston. A similar construction may be provided in the pressure maintained systein to hold the pistons III2 and II I in position of adjustment in the event that the pressure is dissipated by leakage.

Referring now to Fig. 4, the pump 43 discharges to a delivery conduit I32 which has three parallel branches I33, I34 and I35 opening to the bore H9 respectively at the upper end, an intermediate point and the lower end. The pressure conduit III opens to the bore I I9 in'the same transverse plane as the conduit I34. The' piston I22 is formed with an annular groove I36 for connecting the conduits III and I34 when in elevated position, and-is adapted to blank these conduits as well as the conduit I35 when depressed as illustrated in Fig. 4a. As'in the first form, the auxiliary drain con'duit ll'4 ope'ns, to the bore no at a point between the mind H34 and I35, and is adapted to be connected, ough an annular groove I31 and a bleed passage lfl, formed in the piston I22, to the lower end of the bore when the piston is depressed.

A restricted bleed passage I 39 formed in the piston I22 opens at one end to an annular groove I40 in the plunger I23 which is always open .to the auxiliarydraln conduit H4. The other end of the passage 439 is movable into communication fluid tending to leak through the associated bushings.

' Means provided for elevating the stop plunger I23 manually to start the operation of the machine. This means (see Fig. 8) preferably comprises a pin I4I anchored in one side of the piston I22, and extending transversely vtherefrom through a slot I42 in the wall of the bore I13 into the inner end of a bore I43 termed in the front of the apron I. A bushing I44 is secured in the outer end'oi the bore I43, and is termed in its inner end with a straight groove I43 in which the free end of the pin I is guided for vertical movement while being held against angular movement. A rock shaft I48 is ionrna'led In the bushlng I44, and has a crank disk I" on its inner end formed with a notch I48 engaging the pin I4I. Secured on the outer end of the shaft I48 is an operating lever I43 which in its opposed positions is located at one side or the other of its axis. Theweight of the lever I40 therefore tends to hold the valve II in either position of adjustment.

Reversal of the movement of the carriage 2 normally is eifected automatically by the dogs I5 and 10. To permit manual reversal at will, means is provided for reversing the valves II and I2 without regard to the position of the carriage 2.

bore I54 in the apron 55, and which engages in a notch I" in a crank disk I" on the inner end of a rock shaft I51 journaled in the bushing. A hand knob I" is secured to the outer end-of the shaft I51. A spring pressed friction plunger I 59, mounted in a bore I" in the inner end of the bushing I53, engages the adjacent face of the disk I58, and serves to hold the valves SI and 52 in position of adjustment when the operating pressures are dissipated, as for example when the pressure relieved system is inoperative or in the event of leakage over a period of time from the pressure maintained system.

The brake cylinders I4 and I4- are reversely connected in parallel with each other and with the direction valve 3| across the conduits 44 and 45 under the direct control of the valves BI and 82. Similarly, the switch cylinder 26 is connected in parallel with the brake cylinders I4 and I4. Hence, when the carriage 2 in the single end machine is reversed to move toward the spindle head structure (see Fig. 4) the brake band III will be automatically released and the circuit through the coil I6 will be closed. Conversely, upon reversal of the carriage 2 to move in the opposite direction (see Fig. 3), the brake band II will be applied and the motor I will be rendered inoperative.

In the double and machine, the operation is the same for the motor I and thebrake band III with reference to the opposite spindle head structure. Thus, the brake band III' is applied and the coil I6 is deenergized when the band In is released and the coil III is energized, and vice versa.

The hydraulic circuits, more particularly, comprise a branched conduit IBI opening from the conduit 44 respectively to the outer end of the cylinder I4, the inner end of the cylinder I4 and one end of the cylinder 26, and a second branched conduit I62 opening from the conduit 45-respectively to the opposite ends of the cylinders I4, I4 and 26. By.reason of their parallel arrangement with the direction valve 3I, the hydraulic actuators forthe brakes and the motor control switchesare operable without delay, without first awaiting reversal of the valve 3|. upon instituting the reversal of the carriage 2 in either direction. Moreover, they are always subject to a substantial pressure differential under all condltions of machine operation since the opposite ends of each cylinder are always connected respectively to the high pressure side of the system and the drain.

To prevent either of the brake bands I6 and ill from being applied before the associated motor switch is opened, one-way bleed valves I66 and I66 are interposed in the conduits I62 and III respectively at the inlets to the inner ends of the cylinders I6 and II. The bleed valve I66 comprises a chamber I66 having a valve seat I66 opening to the small end of the cylinder I6. Slidable in the chamber I66 is a free floating valve member I66 which has a restricted passage I61 always open to the cylinder I6, and a plurality of longitudinal flutes I66 for the free passage of fluid adapted to be closed by the seat I66. When fluid under pressure is supplied to the conduit I62, the piston 26 will be actuated immediately to open the switch contacts I6, 2i and 26. The piston i6 will also be actuated to apply the brake band ill, but its movement will be retarded by the valve I66. Upon supplying fluid under pressure to the conduit I6I, both pistons I6 and 26 will be actuated simultaneously in the opposite direction. The valve I66 preferably is the same in.

construction as the valve I66 and hence the corresponding parts are identified by the same rel} erence numerals with the exponent "a". The brake and switch means for controlling the operation of the spindle motors 1 and 1 forms the subject matter of and is claimed in my copending divisional application Serial No. 218,668. filed July 13, 1936.

For certain kinds of work, it may be desirable to vary the rate of feed of the carriage 2 in one or the other or both directions. Such is the case particularly where the distance between two work surfaces to be machined is not great enough to warrant the institution of the rapid traverse drive, or where two work surfaces have different machining requirements. In the present instance, a suitable means is illustrated in Fills. 4 and 9 to 11 for automatically adjusting the orifice valve plug 66 upon movement of the carriage 2 through a predetermined zone to the left. To control the rate of feed to the right, a similar means may be substituted for adjusting the orifice valve plug 62, For a control in both directions, duplicate means may be provided respectively for the two plugs 62 and 66. While the feed control means is illustrated as embodied in the pressure maintained system, it is equally well adapted for the pressure relieved system of Fig. 8.

The feed control means in its preferred form comprises a housing I66 adapted to replace the cover plate 6|, and a valve plug similar to the plug 66 except that it is provided with a pinion I16 in place of the head 66. The pinion I16 extends into the housing I66, and meshes with a gear rack Ill formed on one side of a piston I12. The latter is freely reciprocable within a vertical cylinder I16 integral with one end of the housinu I66, and is under the control of a slide valve I16 mounted on the bridge member 6 at the rear of the base I. r

The slide valve I16 comprises a bracket I16 formed with a cylindrical valve bore I16 extending transversely of the carriage 2. Three longitudinally spaced ports I11, I16 and I16 open to the bore I16, and of these, the end ports I11 and I16 are connected respectively through conduits I66 and I6I to the opposite ends of the cylinder I16, while the intermediate port I16 is connected through a conduit I62 to the pressure delivery conduit I62 oi the pump 66. The outer end of thebore I16 is connected through a conduit I66 to the drain conduit 16.

Reciprocably disposed in the bore I16 is I, valve piston I66 formed with two axially spaced collars I66 and I66 defining a peripheral groove I61, and with an axial passage I66 open to its opposite ends. A coiled compression spring I66 seated in one end of the passage I66 tends to move the piston I66 into its left end position as viewed in Fig. 6 in which the groove I61 serves to connect the ports I11 and I16 and the collar I66 uncovers the port I16 for direct communication with the exhaust conduit I66. The connections thus established serve to adjust the oriflce valve into one position, namely. the slow feed position. The piston I66 is adjustable into its opposite end position against the action 0! the spring I66 by an axial plunger I66 extending externally of the bore I16 for engagement by a beveled cam III removably and adjustably mounted on the carriage 2. In this position of the piston I66, the groove I61 serves to connect the ports I16 and I16, and the collar I66 uncovers the port I11 for communication through the passage I66 with the exhaust conduit I66. Thereupon the orifice valve 6i is adjusted into its rapid feed position.

In some instances, for example when it is desired first to bore and then to end face the work, it is desirable to obtain a dwell at one end of the carriage movement. Fig, 4 illustrates a suitable mechanism, optionably available upon rendering' the reversing dog 16 inoperative, for eifecting a predetermined dwell before automatic reversal upon movement of the carriage 2 into its left end position. A similar mechanism may be provided it desired to efiect a dwell at the other end position of the carriage 2 upon rendering the dog 16 inoperative to reverse the drive. The mechanism may be duplicated for dwells at both ends of the carriage movement, and is adaptable to both hydraulic systems herein disclosed.

' Referring to Figs. 4 and 9, a bracket I66 adiustably mounted on the rear of the carriage 2 is located to engage a fixed stop I66 on the bridge member 6 upon movement of the carriage to the leit past the end position normally defined by the dog 16. Engagement of the bracket I62 with the stop I66 defines the dwell position of the carriage 2, and hence the work piece may be properly located by mounting it accurately in relation to the bracket.

The carriage 2 is reversed after a predetermined dwell period by elevating the valve piston 6II.-

Thus, the dwell mechanism comprises a cylinder I66 formed in the screw plug 61, and connected and thereupon the lower end of the bore 66 is connected to exhaust through the conduits 12, 66 and 16 so that the piston 6i in response to the pressure entering the upper end of the bore 66 from the conduit 16 is moved; into its lowermost position as if it were depressed by the dog 16. The supply of fluid under pressure to the conduit I66 is under the control of a dwell valve I61 operable by the carriage 2 as the latter moves into its dwell position.

arsaoco The dwell valve I01 comprises a cylindrical bore I formed in a casing I on the bridge 7 member'l and extending axially in the direction of carriage movement. -A valve piston 200, havlog two spaced heads 2IlI and 2-02 defining an intermediate annular space 201, is slidably disposed in the bore I00, and is normally urged by a spring 204 into an inoperative end position toward the carriage 2. The piston 200 is provided with an actuating plunger normally extending iully projected from the bore I00 for end engagement by a step, 208 on the carriage 2, and upon such engagement is movable against the action 01 the spring 204 into its operative opposite end position. a

Opening to. thebore I00 and the space 202 for all positions of the piston 200 is a supply. conduit 201 connected to the-conduit I22. A drain conduit 200 branching from the conduit Ill opens to one end of the bore I00, and then through an axial passage 200 in the piston 200 to the other bend of the bore. Y The conduit I05 opens to a continuous inner peripheral groove 2" in the end of the bore adjacent the conduit 200. Two conduits 2 II and 2I2 open respectively from the groove 2 I 0 and from the bore I08 intermediate the conduits I05 and 201, and respectively to one end and an intermediate point of a relatively large.

' conduit 2|! is a rotatably adjustable oriilce valve 2li having a peripherally tapered V-shaped groove 2I1 defining a restricted orifice. A piston-2l0 is freely reciprocable in the cylinder 2 I3, and in its opposite end positions is adapted to be located respectively between the conduits 2 I I and M2,, and 2H and 2H.

. When the piston 200 is in inoperative position, the conduits I95, 2 and 2" are open to the drain. conduit 200, the conduits 2H and U5 are open to the space 202, and the conduits 2H and 2-" are in communication through the cylinder 2". Upon movement oi the piston 200 into operative position by the carriage 2,the conduit 2 I is closed by the head 202, the restricted conduit 2'I5 is connected to the exhaust, and the conduit III is connected through the space 203 to the pressure conduit 201. Hence, the piston H0 is moved slowly toward the valve 2l0, thereby affording the desired delay required for the carriage dwell. As soon as the conduit 2 is uncovered by the piston 2i0,.iluid under pressure is directed to the conduit I95 to elevate'the direction valve piston 00, and thereby institute the return movement of the carriage 2. Thereupon, the piston 200 is-returned into inoperative position, and in the course of its movement. the con.- duits 2H and H2 are connected respectively to the pressure and exhaust conduits 201 and .200 to return the piston 2 I0 quickly into initial position.

To provide means for instituting rapid traverse immediately bet-ore, reversal or the carriage 2, the screw plug I00 is formed with a vertical cylinder N0 of larger diameter than the cylinder I04. and also connected to the conduit I00 A piston 220 is reciprocable in the cylinder 2 I0 and carries the stop I08 which is the same in diameter as the stop BlI. It will be seen that, since the piston 220 is larger than the piston I04. the

' diilcrential lii'ting areas of the two pistons are pistons m and :20 will be actuated. but the latter by reason oi its greater pressure differenpressure in the cylinders I00 and 2 I I is dissipated.

the pressure in the lower ends of the bores I2 and I01 will return the stops I8 and I00 into their normal positions. It will be understood that when both reversing dogs 15 and 10 are in operative position, the dwell mechanism will be inoperative. and will not aiiect the normal operation of the hydraulic systemi Patentable subject matter common to this application and my copending application Serial No. 690,525, filed September 22. 1983, is claimed in my said application Serial No. 690,525.

I claim as my invention:

1. An hydraulic operating mechanism for a' reciprocable element of a machine tool comprising, in combination, a reversible hydraulic pis- -ton and cylinder motor ior reciprocating said element, a reversibledirection valve having a free moving piston. a source of fluid under pressure, two pressure passages adapted for connection to said source and leading respectively to said valve at opposite sides or said valve piston, two supply passages leading from said valve between said pressure fluid passages respectively to opposite ends of said motor, an exhaust passage leading from said valve between said supply passages. said valve piston in one end position serving to connect one of said supply passages to one 0! said pressure passages and the other oi said supply passages to said exhaust passage, and in the other end position to connect said other supply-passage to the other of said pressure passages and said one supply passage to said exhaust passage, two restricted passages branchlng respectively from said supply passages, and pilot valve means interposed in said pressure passages and also in said restricted passages and selectively operable to open either pressure passage to said source and connect the other pressure passage and associated restricted passage tosaid exhaust passage whereby to control said valve piston.

2. An hydraulic operating mechanism ior a reciprocable element of a machine tool comprising, in combination, a reversible hydraulic piston and cylinder motor for reciprocating said element, a reversible direction valve having a free moving piston, a source oijiuid under pressure, two pressure passages adapted for connection to said source and leading respectively to said valve at opposite sides of said valve piston, two supply passages leading from said valve.

passages and said one, supply passage to said exhaust passage, and two pilot valves interposed respectively in said pressure passages and adapted for selective actuation by said element, each of said pilot valves upon being actuated by said element acting to' open the associated pressure passage to said ource and to effect movement of the other piio valve into position to connect .in the other end position to connect said other 'supply passage to the other of said pressure the other pressure passage to said exhaust passage whereby to control said valve piston.

3. An hydraulic operating mechanism for a reciprocable element of a machine tool comprising, in combination, a reversible hydraulic piston and cylinder motor for reciprocating said element, a reversible direction valve having a free moving piston, a source of fluid under pressure, two pressure passages adapted for connection to said source and leading respectively to said valve at opposite sides of said piston, two supply passages leading from said valve between. said pressure passages respectively to opposite ends of said motor, an exhaust passage leading from said valve between said supply passages, said valve piston in one end position serving to connect one of said supply passages to one of said pressure passages and the other of said supply passages to said exhaust passage and in the other end position to connect said other supply passage to the other of said pressure passages and said one supply passage to said exhaust passage, two pilot valves interposed respectively in said pressure passages and adapted for selective actuation by said element, each of said pilot valves upon being actuated by said element acting to open the associated pressure passage to said source and to efiect movement of the other pilot valve into position to connect the other pressure passage to said exhaust passage whereby to control said valve piston, and a stop valve adapted for actuation by said element to connect said source to said exhaust passage.

4. An hydraulic operating mechanism for a reciprocable element of a machine tool comprising, in combination, a reversible hydraulic piston and cylinder motor for reciprocating said element, a reversible direction valve having a free moving piston, a source of fluid under pressure, two pressure passages adapted for connection to said source and leading respectively to said valve at opposite sides of said piston, two supply passages leading from said valve between "said pressure passages respectively to opposite ends of said motor, an exhaust passage leading from said valve between said supply passages, said valve piston in one end position serving to connect one 01' said supply passagesjtojjine or said pressure passages and the other of said supply passages to said exhaust passage and in the other end position to connect said other supply passage to the other of said pressure passages and said one supplypassage to said exhaust passage, two pilot valves interposed respectively in said pressure passages and adapted for selective actuation by said element, each of said pilot valves upon being actuated by said element acting to open the associated pressure passage to said source and to efiect movement of the other pilot valve into position to connect the other pressure passage to said exhaust passage whereby to control said valve piston, and a stop valve intenposed between said source and said pilot valves and adapted for actuation by said element to close communication of said pressure passages with said source.

5. An hydraulic operating mechanism for a reciprocable element of a machine tool comprising, in combination, a'reversibie hydraulic piston and cylinder motor for reciprocating said element, a reversible direction valve having a free moving piston, a source oi fluid under pressure, two pressure passages adapted for connection to said source and leadingrespectively to said valve at opposite sides of said valve piston, two

supply passages leading from said valve between said pressure passages respectively to opposite ends or said motor, an exhaust passage leading from said valve between said supply passages, said valve piston in one end position serving to connect one or said supply passages to one of said pressure passages and the other of said supply passages to said exhaust passage and in the other end position to connect said other supply passage to the other of said pressure passages and said one supply passage to said exhaust passage, two restricted exhaust passages branching respectively from said supply passages, two pilot valves interposed respectively in said pressure passages and also in said restricted passages, each pilot valve being adapted for actuation by said element to open the associated pressure passage to said source and close the associated exhaust passage and to eifect movement 0! the other pilot valve into position to connect the other pressure passage to said first mentioned exhaust passage and to open the other restricted exhaust passage, and valve means responsive to the movement of said, element for opening and closing said first mentioned exhaust passage.

6. An hydraulic operating mechanism' for a reciprocable machine tool element comprising, in combination, a reversible hydraulic piston and cylinder motor for reciprocating said element,

two fluid supply passages opening respectively to opposite ends of said motor, a. source of mild under pressure, an exhaust passage, a reversible direction valve movable in opposite directions to connect said source selectively to either of said supply passages and said exhaust passage to the other of said supply passages, two restricted exhaust passages branching respectively from said supply passages, valve means interposed in said restricted passages and operable in synchronism with said reversing valve selectively to close either restricted passage and to open the other restricted passage when the associated supply passages are connected respectiveLv to said source and said first mentioned exhaust passage, and valve means for opening and closing said first mentioned exhaust passage.

7. An hydraulic operating mechanism for a reciprocable machine tool element comprising, in combination, a reversible hydraulic piston and cylinder motor for reciprocating said element, two fluid supply passages opening respectively to opposite ends of said motor, a source or fluid under pressure, an exhaust passage, a reversible direction valve movable in opposite directions to connect said source selectively to either of said supply passages and said exhaust passage to the other of said supply passages, two exhaust passages branching respectively from said supply passages, two independently adjustable orifices interposed respectively in said last mentioned exhaust passages, valve means automatically operable to close either of said last mentioned exhaust passages when the associated supp y passage is connected to said source, and valve means operable upon movement of said element into difierent predetermined positions selectively to open and close said first mentioned exhaust passage.

8. An hydraulic operating mechanism for a reciprocable machinetool element comprising,

in combination, a. reversible hydraulic piston and opposite ends of said motor, a source or fluid n under pressure, an exhaust passage, a reversible direction valve movable in opposite directions to connect said source selectively to either of said supply es and said exhaust passage to the other of said supply passages, two exhaust passages 'branching'respectively from said supply passages, two independently adjustable orifices interposed respectively in said last mentioned exhaust passages, two valves interposed respectively in said last mentioned exhaust passages, each 01' said last mentioned valves being adapted for selective actuation by said element to close one of said last mentioned exhaust passages when the associated supply passage is connected to said source and to eflect movement 01' the other of said last mentioned valves into position to open the other of said last mentioned exhaust passages, and valve, means selectively operable to open and close said first mentioned exhaust m P583386.

9. An hydraulic-operating mechanism for a reciprocable machine tool element comprising, in

combination, a reversible hydraulic piston' and cylinder motor for reciprocating said element, two fluid supply passages leading respectively to opposite ends of said motor, a source of liquid 'fluid under pressure, an unrestricted exhaust passage, two restricted exhaust passages each including an independently adjustable restriction so orifice, and valve means for connecting said source and said unrestricted exhaust passage alternately and reversibly to said supply passages and for effecting the discharge of exhaust fluid i'romsaid motor selectively through said unrestricted exhaust passage or alternately through said restricted exhaust passages. V 10, An hydraulic operating mechanism for a reciprocable machine tool element comprising, in combination, a reversible hydraulic piston and cylinder motor for reciprocating said element, two

fluid supply passages leading respectively to opposite ends of said motor, a source of liquid fluid under pressure, an unrestricted exhaust passage,

5o passage or one of said orifices while preventing the discharge of fluid from said one supplypassage through the other of said orifices, and upon movement oi said element into the other end position to connect said other supply passage to said source 55 and to eflect the discharge of fluid from said one supply passage through said exhaust passage or said other of said oriflces'while preventing the d scharge of fluid from said other sup'ply passage through said one of said orifices, and valve means 90 selectively operable to open and close said exhaust passage. 7 I

11. An hydraulic operating mechanism' tor a reciprocable machine tool element comprising, in combination, a reversible hydraulic piston and as cylinder motor for reciprocating said element, two

fluid supply passages leading respectively to opposite ends 0! said motor, a source of liquid fluid under pressure, an unrestricted exhaust passage, exhaust means including two restriction orifices, 70 multiple direction control valve means automatically operable upon movement of said element into one end position to connect one of said supply passages to said source and to eiiect the discharge of fluid from the other of said supply passages 76 through said exhaust passage or one 01 said orifices while preventing the discharge of fluid from said one supply passage through the other oi said orifices, and upon movement oi said element into the other end position to connect said other supply passage to said source and to eifect the discharge oi fluid from said one supply passage through said exhaust passage or said other of said orifices while preventlrig the discharge of fluid from said other supply passage through said one of said orifices, said orifices being independently adjustable so 10 that the rate of movement of said element may be regulated to be equal in both directions or selectively greater in either direction thanin the other, and valve means selectively operable to open and close said exhaust passage. 15 12. An hydraulic operating mechanism for a reciprocable machine tool element comprising, in combination, a reversible hydraulic piston and cylinder motor for reciprocating said element, two fluid supply passages opening respectively to op- 20 p'osite ends of said m'otor, a source of fluid under pressure, an exhaust e, a reversible direction valve movable in opposite directions to connect said source selectively to either of, said supply passages and said exhaust passage to the other of as said supply passages, two exhaust passages branching respectively from said supply passages,

two independently adjustable orifices interposed respectively in said last mentioned exhaust passages, valve means automatically operable to close 80 either of said last mentioned exhaust passages when the associated supply passage is connected to said source, valve means operable upon movement of said element into different predetermined positions selectively to open and close said first 85 mentioned exhaust passage, and means automatically operable upon movement of said element into a predetermined position to adjust one of said orifices.

13. An hydraulic operating mechanism for a 40 reciprocable element of a machine tool comprising, in combination, an hydraulic motor for driving said element, means for supplying fluid under pressure to said motor, means for exhausting fluid from said motor and including an adjustable restriction orifice for controlling the rate of travel of said element, said orifice comprising a rotary valve member having a tapered peripheral port coactin'g with a registering'port, a pinioncoaxially fixed on said member, a-gear rack meshing with said pinion, a piston and cylinder unit for reciprocating said rack, valve means for directing fluid under pressure selectively to opposite ends of said unit,-and means for adjusting said valve means in response toizhc movement 01' said element into different predetermined positions.

14. An hydraulic operating mechanism for a reciprocable element of a machine tool comprise ing, in combination, an hydraulic motor tor, driving said element, means for supplying fluid under pressure to said motor, means for exhausting fluid from said motor and including an adjustable restriction oriflce for controlling the rate of travel of said element, said orifice comprising a valve member having a tapered port adjustablelongiq .tudinally across a registering port, a piston 'and' cylinder unit 'for adjusting said valve member selectively into either..o:l two positions, valve I means for directing fluid under pressure selectively to either end of said unit and simultaneousiy to open the other end of said unit to exhaust,

and means for adjusting said valve means in movable machine tool element, control means "mounted on said element for movement therewith.

pressure fluid passages cross-connecting said. cas-- ings and controlled by said members to automatio' cally return either member into operative position upon movement of the other member into inoperative position by said means, and detent means for yieldabiy holding said valve members in position of adjustment.

16. In an hydraulic operating mechanism for a movable machine tool element, control means mounted on said element for movement therewith, two pilot valves mounted in fixed position and each having a casing and a valve member movable therein and projecting therefrom, each member having an inoperative position and an operative position ior engagement by said means, pressure fluid passages cross-connecting said casings and controlled by said members to automatically return either member into operative position upon movement of the other member into inoperative position by said meansfiand manual means for adjusting one of said valve members into either of its positions.

17. In an hydraulic operating mechanism for a a movable machine tool element, control means mounted 'on said element for movement therewith, two pilot valvesmounted in fixed position and each having a casing and a valve member movable therein and projecting thereirom, each member having an inoperative position and an operative position for engagement by said means, pressure ,fluld passages cross-connecting said casings and controlled by said members to automatically return either member into operative position upon movement of the other member into inoperative position by said means, a piston and cylinder unit for adjusting one of said valve members from inoperative position into operative position, and valve means for supplying fluid under pressure to said unit.

18. An hydraulic operating mechanism for a movable machine tool element, a base for supporting said element, a piston and cylinder motor for driving said element, valve means including two pilot valves mounted in fixed position on said base and operable respectively to eflect reverse movements of said element, each pivot valve comprising a casing and a valve member movable therein and projecting therefrom, control means on said element, each member having an inoperative position and an operative position for engagement by said control means, a source of fluid under pressure, two passages cross-connecting said casings and controlled bysaid members for selective connection to said source to automatically return either member into operative position upon movement of the other member into inoperative position by said control means, said control means being adjustable on occasion to be ineiiective to adjust one t, said members into inoperative position, and automatic means operable by said element to provide a dwell for said element and then to elevate the other of said members into operative position to effect a delayed reversal of said element.

' 19. A machinetool comprising, in combination.

, a base, a carriage reciprocable on said base, 'an

hydraulic motor for reciprocating said; carriage,

a control system for said motor and including a member adapted tor actuation to effect reversal oi movement of said carriage, an abutment normally coasting with said member upon movement 0! said carriage into a predetermined end position to eflect such reversal, and being capable of relative adjustment out of cooperative relation with said member to permit additional movement 0! said carriage past said end position, abutment means for stopping said carriage in a second predetermined end position at the end of said additional movement. and means automatically operable to provide a predetermined dwell tor said carriagein said second end position and then to actuate said control system to eiiect said reversal of movement. a

20. A machine tool comprising, in combination a base. a carriage reciprocable on said base, an hydraulic motor for reciprocating said carriage, a control system for said motor and imlnding a member adapted for actuation to efiect reversal of movement 01' said carriage, an abutment normally coacting with said member upon-movement of said carriage into a predetermined end position to effect such reversal, and being capable of relative adjustment out of cooperative relation with said'member to-permit additional movement oi said carriage past said end position, abutment means for stopping said carriage in a second predetermined end position at the end of said additional movement, a time device for actuating said control system after a dwell period to eflfect said reversal oi movement, and means operable by said carriage as an incident to said additional movement to institute operation of said time device;

21. A machine tool comprising, in combination, a base. a carriage reciprocable on said base, an hydraulic motor for reciprocating said carriage, an hydraulic control system for said motor and including a valve adapted for actuation to eflect reversal of movement of said carriage, an abutment on said carriage normally in position to actuate said valve upon movement of said carriage into a predetermined end position, and being capable of adjustment out oi cooperative relation with said valve to permit an additional movement of said carriage past said end position, abutment means for stopping said carriage in a second predetermined endposition at the end 01' said additional movement, means including a piston and cylinder unit for actuating said valve to effect said reversal of movement, a source of fluid under pressure, a time delay device operable to connect said source to said unit after a dwell'period, and a valve operable by said carrlage as an incident to said additional movement to initiate operation of said delay device to institute operation of said delay device.

22. A machine tool comprising, in combination, a base, a carriage reciprocable on said base, an hydraulic motor for reciprocating said carriage, an hydraulic control system ior said motor and including a valve adapted for actuation to effect reversal of movement of said carriage, abutment means for stoppingsaid carriage in a predetermined end position, means including a,.piston and cylinder unit for actuating said valve to eflect said reversal of movement, a source of fluid under pressure, a time delay device operable to connect said source to said unit after a dwell period. and a valve operable by said carriage as an incident to movement into said end position to institute operation of said delay device.

23. A machine tool comprising, in combination, a base, a movable element on said base, a piston and cylinder unit for driving said element, a source of fluid under pressure, a main exhaust passage, fluid passages leading to opposite ends 01' said unit, a direction valve operable selectively to connect said fluid passages respectively and reversibly to said source and said exhaust, a fluid pressure responsive valve in said exhaust passage, abutment means on said element for actuating said last mentioned valve in one direction to open said exhaust passage, a valve operable by said abutment means to direct fluid pressure to said last mentioned valve to close said exhaust passage, and restricted flow means for exhausting fluid from said unit when said exhaust passage is closed.

24. In an hydraulic operating mechanism for a movable machine tool element, control means mounted on said element for movement therewith, two pilot valves mounted in fixed position and each having a casing and a valve member movable therein and projecting therefrom, each member having an inoperative position and an operative position for engagement by said means, pressure fluid passages cross-connecting said casings and controlled by said members to automaticaliy return either member into operative position upon movement of the other member into inoperative position by said means, manual means for adjusting one of said valve members into either or its positions, and means for yieldably holding one of said valve members in position of adjustment.

25. In an hydraulic operating mechanism for a movable machine tool element, control means mounted on said element for movement therewith, two pilot valves mounted in fixed positionand each having a casing and a valve member movable therein and projecting therefrom, each member having an inoperative position and an operative position for engagement by said means, pressure fluid passages cross-connecting said casings and controlled by said members to automatically return either member into operative position upon movement ,of the other member into inoperative position by said means, and automatic means operable upon movement of said element into a predetermined position and effective after a predetermined delay to adjust one of said valve members from one position into the other position. i

26. In a hydraulic operating mechanism for a movable machine tool element, control means mounted on said element for movement therewith, a control valve mounted in a fixed position and having a casing and a valve member movable therein and projecting therefrom, said member having an inoperative position and an operative position for engagement by said means, a cylinder on said casing, a piston in said cylinder and having a stop normally defining said inoperative position, and means for supplying pressure fluid to said cylinder to adjust said stop and thereby project said member into said operative position.

CARROLL R. ALDEN.

CERTIFICATE OF CORRECTION.

Patent no. 2,153,060.

CARROLL R. ALDEN.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: la'ge 2, second column', line 0, for "conduit" read conduit 0; e eg, first column, line 12, for "ifroiu' read for; page 1-0, first column, line 53, claim 18, for "pivot" readpilot; and that the said Letters Patent should be read this correction therein that the same may conform to the record of the case in the Patent Office.

Signed andseaied this 1st day of August A. D. 1959.

(Seal) Henry Van 'Arsdale, Acting qcmissioner or Patents. 

